Constructive Electroactive 2D/2D MoS2-N-rGO and 1D/2D Bi2S3-N-rGO Heterostructure for Excellent Mo-Bi Supercapattery Applications

Metal sulfides including MoS2 and Bi2S3 materials, have been considered as a strong candidate for supercapacitor applications. However, the short-term stability and low surface area have limited the establishment of such eco-friendly materials in energy storage. In this work, an effective strategy is designed to in-situ combine transition metal sulfides with nitrogen doped reduced graphene oxide hydrogels and improve the overall supercapattery properties. Precisely, MoS2-N-rGO and Bi2S3-N-rGO hydrogels have been developed via hydrothermal route. The morphological analysis manifests two-dimensional 2D/2D heterostructure for the MoS2-N-rGO and 1D/2D heterostructure for the Bi2S3-N-rGO. The cyclic voltammetry studies showed a battery-like electrochemical behavior for the synthesized hydrogels. The calculated capacitance for MoS2-N-rGO and Bi2S3-N-rGO are about 438 F/g and 342 F/g @ 1 A/g with 50% and 41% of their capacitance initial values @ 20 A/g, respectively. The cycling performance showed that MoS2-N-rGO and Bi2S3-N-rGO can maintain 90% and 98% of their original specific capacitance after 1000 cycles life. Furthermore, the supercapattery device was fabricated using MoS2-N-rGO as cathode and Bi2S3-N-rGO as anode. The hybrid device is capable of offering 33.4 Wh/kg energy density, at 0.85 kW/kg power density, with 44.7% retention at 20 A/g. Notably, the overall electrochemical behavior of Mo-Bi supercapattery device is remarkable among the pointed behaviors for other hybrid devices.